linux/net/ipv4
Yong Wang 870a9e42ec tcp: clamp route advmss to TCP_MIN_MSS
tcp_select_initial_window() assumes that callers never pass an MSS
smaller than 1, but route-derived advmss values can violate that
assumption.

A too-small explicit RTAX_ADVMSS is one way to get there, but it is not
the only one. The same divide-by-zero can also be reached through the
"default advmss" path when RTAX_ADVMSS is left at 0 and the effective
advmss is later driven down by route MTU and min_adv_mss.

Introduce a tcp_dst_advmss() helper that clamps route advmss to
TCP_MIN_MSS before TCP consumes it, and use it in the TCP paths that
derive advmss from dst metrics. This keeps the effective MSS from
dropping to zero before tcp_select_initial_window() rounds the receive
window.

Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org
Reported-by: Vega <vega@nebusec.ai>
Signed-off-by: Yong Wang <edragain@163.com>
Signed-off-by: Ren Wei <weir@nebusec.ai>
Link: https://patch.msgid.link/251eaf8277fa7c66364c9815c5da01662d269181.1787074852.git.edragain@163.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-08-22 13:05:19 -07:00
..
netfilter netfilter: nf_tables: call skb_valid_dst() before skb_dst() 2026-07-31 14:47:03 +02:00
af_inet.c ipv4: remove obsolete EXPORT_SYMBOL() and EXPORT_SYMBOL_GPL() 2026-06-05 17:47:07 -07:00
ah4.c xfrm: ah: use skb_to_full_sk in async output callbacks 2026-05-16 10:56:14 +02:00
arp.c net: remove ax25 and amateur radio (hamradio) subsystem 2026-04-23 10:24:02 -07:00
bpf_tcp_ca.c bpf: Reject TCP_NODELAY in bpf-tcp-cc 2026-04-22 12:58:57 -07:00
cipso_ipv4.c Convert remaining multi-line kmalloc_obj/flex GFP_KERNEL uses 2026-02-22 08:26:33 -08:00
datagram.c raw: annotate lockless match fields in raw_v4_match() 2026-07-23 07:46:12 -07:00
devinet.c net: Const qualify ctl_tables that kmemdup unconditionally 2026-08-13 13:12:24 +02:00
esp4_offload.c xfrm: Fix inner mode lookup in tunnel mode GSO segmentation 2025-12-04 09:54:53 +01:00
esp4.c net: Use helpers to get/set UDP len tree-wide 2026-07-22 13:47:02 +02:00
fib_frontend.c ipv4: fib: Define fib_table_hash_lock under CONFIG_IP_MULTIPLE_TABLES. 2026-07-07 10:51:06 +02:00
fib_lookup.h ipv4: fib: Annotate access to struct fib_alias.fa_state. 2026-01-28 19:33:07 -08:00
fib_notifier.c net: do not acquire rtnl in fib_seq_sum() 2024-10-11 15:35:05 -07:00
fib_rules.c net: fib_rules: Only hold RTNL for the first IPv4 RTM_NEWRULE. 2026-07-01 18:42:34 +02:00
fib_semantics.c ipv4: fix use-after-free in fib_nhc_update_mtu() 2026-08-11 11:25:10 +02:00
fib_trie.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2026-07-20 09:18:11 +02:00
fou_bpf.c
fou_core.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2026-07-30 12:53:19 -07:00
fou_nl.c fou: Don't allow 0 for FOU_ATTR_IPPROTO. 2026-01-17 16:00:24 -08:00
fou_nl.h tools: ynl-gen: add regeneration comment 2025-11-25 19:20:42 -08:00
gre_demux.c gre: Count GRE packet drops 2026-04-12 12:33:33 -07:00
gre_offload.c
icmp.c ipv4: icmp: fill flow parameters in icmp_route_lookup decoy lookup 2026-07-23 07:01:24 -07:00
igmp_internal.h netlink: support dumping IPv4 multicast addresses 2025-02-11 11:26:53 +01:00
igmp.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2026-07-10 10:20:05 +02:00
inet_connection_sock.c tcp: fix TFO max_qlen accounting across reuseport migration 2026-08-05 17:10:28 -07:00
inet_diag.c inet_diag: report delayed ack timer information 2026-03-06 16:32:26 -08:00
inet_fragment.c inet: frags: publish queues before arming timer 2026-07-31 17:05:07 -07:00
inet_hashtables.c net: remove some unused EXPORT_SYMBOL()s 2026-06-12 16:43:11 -07:00
inet_timewait_sock.c inet: Avoid ehash lookup race in inet_twsk_hashdance_schedule() 2025-10-17 16:08:43 -07:00
inetpeer.c inetpeer: randomize RB-tree node comparison using SipHash 2026-08-20 12:55:31 -07:00
ip_forward.c
ip_fragment.c inet: frags: fix use-after-free caused by the fqdir_pre_exit() flush 2026-06-04 18:05:23 -07:00
ip_gre.c gre: fix ERSPAN o_flags race/corruption in xmit and fill_info 2026-08-14 12:57:44 -07:00
ip_input.c tcp: move tcp_v4_early_demux() to net/ipv4/ip_input.c 2026-03-09 18:50:24 -07:00
ip_options.c ipv4: restrict IPOPT_SSRR and IPOPT_LSRR options 2026-06-03 18:53:14 -07:00
ip_output.c ipv4: reject undersized MTUs in ip_do_fragment() 2026-08-18 09:12:56 -07:00
ip_sockglue.c net: remove addr_len argument of recvmsg() handlers 2026-03-02 18:17:17 -08:00
ip_tunnel_core.c tunnels: do not assume transport header in iptunnel_pmtud_check_icmp() 2026-05-26 18:11:47 -07:00
ip_tunnel.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2026-08-18 10:42:41 -07:00
ip_vti.c net: ip_vti: require CAP_NET_ADMIN in the device netns for changelink 2026-06-17 16:01:52 -07:00
ipcomp.c xfrm: add extack to xfrm_init_state 2026-06-04 12:22:35 +02:00
ipconfig.c net: Use helpers to get/set UDP len tree-wide 2026-07-22 13:47:02 +02:00
ipip.c ipip: fix skb leak in collect_md mode when metadata_dst allocation fails 2026-08-22 13:03:10 -07:00
ipmr_base.c ipmr: Replace use of system_unbound_wq with system_dfl_wq 2026-05-19 18:21:39 -07:00
ipmr.c ip: orphan prefetched skbs before multicast forwarding 2026-08-18 13:05:14 +02:00
Kconfig net/tcp: Remove tcp_sigpool 2026-04-30 09:38:56 +02:00
Makefile netfilter: add option for GCOV profiling 2026-05-24 22:55:47 +02:00
metrics.c net: remove EXPORT_IPV6_MOD() and EXPORT_IPV6_MOD_GPL() macros 2026-03-29 11:21:22 -07:00
netfilter.c net: Add SPDX ids to some source files 2026-03-09 18:32:45 -07:00
netlink.c
nexthop.c ipv4: nexthop: handle errors in nexthop_init() 2026-08-04 18:33:17 -07:00
ping.c Networking changes for 7.1. 2026-04-14 18:36:10 -07:00
proc.c udp: Remove UDP-Lite SNMP stats. 2026-03-13 18:57:44 -07:00
protocol.c
raw_diag.c inet_diag: change inet_diag_bc_sk() first argument 2025-08-29 19:29:24 -07:00
raw.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2026-07-23 14:07:40 -07:00
route.c net: advertise TCP MSS from the configured MTU, not the learned PMTU 2026-08-20 12:14:23 -07:00
syncookies.c tcp: rehash onto different local ECMP path on retransmit timeout 2026-06-15 15:57:31 -07:00
sysctl_net_ipv4.c net: Const qualify network templated ctl_tables Arrays 2026-08-13 13:12:24 +02:00
tcp_ao.c net/tcp-ao: fix use-after-free of current_key on reconnect to another peer 2026-08-20 12:18:12 -07:00
tcp_bbr.c tcp_bbr: fix SPDX-License-Identifier to be GPL-2.0 OR BSD-3-Clause 2026-06-01 16:51:08 -07:00
tcp_bic.c tcp: annotate data-races around tp->snd_ssthresh 2026-04-18 11:10:12 -07:00
tcp_bpf.c bpf, sockmap: Fix sk_redir use-after-free in send verdict 2026-08-01 18:24:58 +02:00
tcp_cdg.c tcp: annotate data-races around tp->snd_ssthresh 2026-04-18 11:10:12 -07:00
tcp_cong.c tcp: ECT_1_NEGOTIATION and NEEDS_ACCECN identifiers 2026-02-03 15:13:24 +01:00
tcp_cubic.c tcp: annotate data-races around tp->snd_ssthresh 2026-04-18 11:10:12 -07:00
tcp_dctcp.c tcp: annotate data-races around tp->snd_ssthresh 2026-04-18 11:10:12 -07:00
tcp_dctcp.h net: Add SPDX ids to some source files 2026-03-09 18:32:45 -07:00
tcp_diag.c inet_diag: report delayed ack timer information 2026-03-06 16:32:26 -08:00
tcp_fastopen.c net: remove EXPORT_IPV6_MOD() and EXPORT_IPV6_MOD_GPL() macros 2026-03-29 11:21:22 -07:00
tcp_highspeed.c
tcp_htcp.c
tcp_hybla.c
tcp_illinois.c
tcp_input.c tcp: fix icsk_ack.ato bitfield overflow 2026-08-10 16:02:30 -07:00
tcp_ipv4.c tcp: clamp route advmss to TCP_MIN_MSS 2026-08-22 13:05:19 -07:00
tcp_lp.c net: tcp_lp: fix kernel-doc warnings and update outdated reference links 2025-10-28 17:52:44 -07:00
tcp_metrics.c tcp: annotate data-races around tp->snd_ssthresh 2026-04-18 11:10:12 -07:00
tcp_minisocks.c tcp: clamp route advmss to TCP_MIN_MSS 2026-08-22 13:05:19 -07:00
tcp_nv.c tcp: annotate data-races around tp->snd_ssthresh 2026-04-18 11:10:12 -07:00
tcp_offload.c gro: flushing when CWR is set negatively affects AccECN 2026-02-03 15:13:24 +01:00
tcp_output.c tcp: clamp route advmss to TCP_MIN_MSS 2026-08-22 13:05:19 -07:00
tcp_plb.c tcp: rehash onto different local ECMP path on retransmit timeout 2026-06-15 15:57:31 -07:00
tcp_recovery.c tcp: move tcp_rack_advance() to tcp_input.c 2026-01-28 19:31:51 -08:00
tcp_scalable.c
tcp_timer.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2026-08-13 11:00:14 -07:00
tcp_ulp.c
tcp_vegas.c tcp: annotate data-races around tp->snd_ssthresh 2026-04-18 11:10:12 -07:00
tcp_vegas.h tcp: add cwnd_event_tx_start to tcp_congestion_ops 2026-03-24 21:00:38 -07:00
tcp_veno.c tcp: add cwnd_event_tx_start to tcp_congestion_ops 2026-03-24 21:00:38 -07:00
tcp_westwood.c tcp: annotate data-races around tp->snd_ssthresh 2026-04-18 11:10:12 -07:00
tcp_yeah.c tcp: annotate data-races around tp->snd_ssthresh 2026-04-18 11:10:12 -07:00
tcp.c net: tcp: block mixing readable and unreadable frags 2026-08-20 13:22:14 -07:00
tunnel4.c
udp_bpf.c sockmap: Fix use-after-free in udp_bpf_recvmsg() 2026-06-14 21:30:20 -07:00
udp_diag.c udp: Don't pass udptable to IPv4 socket lookup functions. 2026-03-13 18:57:46 -07:00
udp_offload.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2026-08-06 11:53:47 -07:00
udp_tunnel_core.c udp: Set length in UDP header to 0 for big GSO packets 2026-07-22 13:47:02 +02:00
udp_tunnel_nic.c net: udp_tunnel: fix memory leak in udp_tunnel_nic_unregister() 2026-07-28 13:32:34 +02:00
udp_tunnel_stub.c
udp.c Merge branch 'big-tcp-for-udp-tunnels' 2026-07-22 13:49:03 +02:00
xfrm4_input.c xfrm: Fix dev use-after-free in xfrm async resumption 2026-06-12 08:39:59 +02:00
xfrm4_output.c ipv4: adopt dst_dev, skb_dst_dev and skb_dst_dev_net[_rcu] 2025-07-02 14:32:30 -07:00
xfrm4_policy.c net: Const qualify network templated ctl_tables Arrays 2026-08-13 13:12:24 +02:00
xfrm4_protocol.c ipv4: Convert ip_route_input_noref() to dscp_t. 2024-10-03 16:21:21 -07:00
xfrm4_state.c
xfrm4_tunnel.c